How would you solve the boring "damage rotation" of the healers?

[AmiableApkallu]

But for my personal tastes and my opinion, the ideal outcome would be one where the spells healers cast in content matched to their skill level are almost entirely healing spells, save for an appropriate amount of wiggle room.

Care to take on ty's challenge, then? It's an easier ask than your ideal outcome, as he's looking for merely more healing GCDs than Dosis GCDs. (Personally, I'd accept, at least as a starting point, any sort of hypothetical encounter + hypothetical job design.)

Anyone who's actually run healers through Duty Finder can tell you that the "wiggle room" you speak of is quite wide. S-tier parties will leave you bored to tears. Trash-tier parties will starve you of resources faster than you get them back.